Airbag for head protection

ABSTRACT

An airbag system including an airbag and a detachable shell enclosing the airbag when the airbag is in a non-inflated state, and at least one size adjustment mechanism. Further, an inflatable helmet having such airbag system, and an item of apparel having such airbag system are provided.

TECHNICAL FIELD

The present invention relates to airbags. More specifically, the present invention relates to a wearable airbag for protecting a user's head.

BACKGROUND

Airbags for protection of a person's head are known in the art, for example through DE19754541A1 and through WO01/54523A1. A problem with these devices is that it is not adaptable for different users. Different users have different physical dimensions, such as width or length of the neck. Also, different users are comfortable with different tightness of the device when worn. A user may also want to adapt the size of the device according to the clothes he/she is wearing. Bulky winter clothes could require a larger sized device, whereas light summer clothes could allow for a smaller sized device.

It would therefore be beneficial for the user to be able to adapt the size of the device to his/her specific needs.

SUMMARY

An object of the present invention is to provide a new type of airbag system which is improved over prior art and which eliminates or at least mitigates the drawbacks discussed above. More specifically, an object of the invention is to provide an airbag system that is ergonomic and adaptable to different users. These objects are achieved by the technique set forth in the appended independent claims with preferred embodiments defined in the dependent claims related thereto.

In a first aspect of the invention, an airbag system is provided, the system comprising an airbag which upon inflation forms a helmet. The system further comprises a detachable shell enclosing the airbag when the airbag is in a non-inflated state and at least one size adjustment means. This airbag system is advantageous in that the size of the system is adjustable such that it can be adapted to suit different users.

In one embodiment, the size adjustment means is arrangeable between the airbag and the shell. This provides for easy access to the size adjustment means such that the size is easily adjustable.

The airbag system may be arranged as a collar, and the size adjustment means may be arranged to adjust the diameter of the collar from a larger diameter to a smaller diameter. The collar is thus adjustable such that it suits different users.

In one embodiment, the at least one size adjustment means comprises a set of pads which are arrangeable between the airbag and the shell, or on the exterior surface of the shell facing the user. By arranging the pads in the airbag system, the size of the system is adapted to the individual conditions for every user. The user may himself choose how many pads to use. Different sizes of pads or elongate pads may be provided such that different adjustments may be obtained. This is advantageous if the user wants several adjustment options.

The at least one size adjustment means may comprise an elongate pad which is arrangeable between the airbag and the shell, or on the exterior surface of the shell facing the user. The size of the airbag system may thus be adapted.

Alternatively, the at least one size adjustment means comprises an elastic band or strap, arrangeable between the airbag and the shell, or on the exterior surface of the shell facing the user.

Additionally, the size adjustment means may comprise a set of additional detachable shells having smaller sizes compared to the detachable shell. By using another shell, it is possible to adjust the collar according to the physical dimensions and properties of the user, or according to other items worn by the user.

In one embodiment, the size adjustment means is an inflatable tube, and further, the airbag system comprises a valve for inflation of the inflatable tube. The valve provides for different amount of air being provided in the inflatable tube, and the size of the collar is thus continuously adjustable.

Preferably, the airbag system further comprises a pump for inflation of the inflatable tube. This has the advantage that the pump is always available if a size adjustment is required.

In a preferred embodiment, the size adjustment means comprises a band or strap, arrangeable between the airbag and the shell, or on the exterior surface of the shell facing the user.

The airbag system may further comprises a strap fastening means arranged at an end of the collar to fasten the at least one strap such that each strap is divided into two loops with the strap fastening means between them. This has the advantage that the loops are easy and intuitive to manipulate, and the size of the collar is continuously adjustable.

Preferably, the airbag system comprises a strap fastening means arranged at an end of the collar to fasten an at least one strap arranged through the fastening means, wherein the fastening means comprises a spool member inside a housing and the strap is secured to the spool member. This has the advantage that there are no loose ends and continuous and intuitive control over the size of the collar is achieved. Each of the above options provides a user with the ability to adjust the collar according to the physical dimensions and proportions of the user, or according to other items worn by the user.

In a second aspect of the invention, an inflatable helmet is provided comprising the above airbag system. It is preferred that it is possible to adjust the size of the inflatable helmet. This is possible with such an airbag system.

In a third aspect of the invention, an item of apparel is provided comprising the above airbag system. It is preferred that it is possible to adjust the size of the item of apparel. This is possible with such an airbag system.

In one embodiment, the item of apparel is a collar. This is beneficial since it is an item worn by the user in the near his/her head, which is to be protected by the airbag of the airbag system.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described in the following; references being made to the appended diagrammatical drawings which illustrate non-limiting examples of how the inventive concept can be reduced into practice.

FIG. 1a is a schematic view of a user wearing an inflatable helmet according to some embodiments;

FIG. 1b is a schematic view of a user wearing an inflated helmet according to some embodiments;

FIGS. 2a-c are schematic views of different resting positions according to different embodiments;

FIG. 3 is a cross section of a collar according to an embodiment;

FIG. 4 is a cross-sectional top view of the collar not being size adjusted;

FIG. 5 is a cross-sectional top view of the collar in FIG. 4 with size adjustment means according to one embodiment;

FIG. 6 is a cross-sectional top view of the collar in FIG. 4 with size adjustment means according to one embodiment;

FIG. 7 is a side view of the collar in FIG. 4 and a size adjustment means before insertion into the collar;

FIG. 8 is a cross-sectional top view of the collar in FIG. 4 with size adjustment means according to one embodiment;

FIG. 9 is a side view of the collar of FIG. 4 with size adjustment means according to one embodiment;

FIG. 10 is a side view of the collar in FIG. 9 with adjusted size adjustment means;

FIG. 11 is a side view of the collar of FIG. 4 with adjusted size adjustment means according to one embodiment;

FIG. 12 is a side view of a collar with size adjustment means according to one embodiment;

FIGS. 13a-b are side views of a collar with size adjustment means according to one embodiment;

FIG. 14 is a side view of a collar with size adjustment means according to one embodiment; and

FIG. 15 is a side view of a collar with size adjustment means according to one embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, certain embodiments will be described more fully with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention, such as it is defined in the appended claims, to those skilled in the art.

FIG. 1a shows an airbag system 10 suitable for bicycle riders according to an embodiment in its non-inflated state. Further, an item of apparel 11 is schematically shown in FIG. 1a . The item of apparel 11 has the shape of a collar which is worn around the neck 2 of a user 3. Thus, the collar 11 is intended to be worn on top of other clothes around the neck of the user 3 as a preventive measure in case of an accident. The collar 11 encloses a folded airbag 20 in an uninflated state, which is inflated to form a helmet 100 when electronic circuitry, also enclosed within the collar 11, determines that the movement of the collar 11, and hence the movement of the user 3, corresponds to a predetermined accident movement. Thus, the head region of the user 3 is protected in case of an accident. For the inflation of the airbag 20 a gas inflator is arranged inside the collar 11 and connected to the airbag 20.

As is also shown in FIG. 1a , the apparel 11 may comprise a joint portion provided with an interlocking means 12, such as a zipper, Velcro or releasable male/female connectors to connect the ends of the apparel 11 e.g. adjacently the user's 3 throat or neck region. The interlocking means 12 facilitates easy dressing and undressing of the apparel 11 on the user 3. In one embodiment, the interlocking means connects the ends of the apparel 11 e.g. adjacently the user's 3 throat or neck region. The interlocking means comprises a first fastening body and a second fastening body, where one end of the first and second fastening body are each connected to the apparel 11. The apparel 11 is thus easily attached to the neck of the user by attaching the first fastening body and the second fastening body to each other, and the apparel 11 is released from the neck of the user 3 by detaching the first and second fastening bodies from each other. In a preferred embodiment, the first and second fastening body are a female and male connector.

In some embodiments, the position of the different parts of the interlocking means may determine if the airbag system configured to controlling the inflation of the airbag is turned on (i.e. having power) or turned off, and if its turned on in an active state or in an idle state. The interlocking means is configured to be arranged in a first locking position or a second locking position when the first fastening body and the second fastening body are connected to each other. When the interlocking means is in a first locking position, the system is automatically put into an idle state and when the interlocking means is in a second locking position, the system is automatically put into an active state.

The inflated airbag helmet 100 is schematically shown in FIG. 1b . Here, the collar 11 is opened to release the airbag 20 previously enclosed therein. The airbag 20 surrounds the neck 2 and the head 4 of the user 3 and provides an efficient protection for the user 3.

The airbag 20 may e.g. comprise an inner bag suitable for inflation surrounded by an outer bag. Both the inner bag and the outer bag are formed of a flexible material in order to be folded and stored within the collar 11 prior to inflation. The inflated helmet 100 shape of the airbag 20 must therefore by defined by the flexible airbag 20 itself, which previously required complex sewing techniques of an outer bag surrounding the inner bag.

The method of constructing the airbag comprises forming the helmet shaped airbag 100 having a head and neck protecting shape from a substantially flat piece of material.

Construction of the airbag 20 may e.g. be performed by sewing the seams of the airbag whilst the airbag is maintained in a flat format. Optionally, the airbag may be manufactured by a one piece woven material such that a flat bag is formed. By constructing the airbag 20 with the material in a flat format the costs and complexity associated with sewing are reduced.

Examples of how to provide the airbag as a double-bag configuration is disclosed in WO2012044245 by the same applicant.

When the airbag system is not worn by the user, the collar 11 can be put in a resting position to allow the user to carry the collar 11 easier for example by putting it in a bag. All electronics in the airbag system is turned off when the airbag system is put in the resting position. In the resting position the collar is connected such that the diameter of the collar is greatly reduce as is shown in the exemplary embodiments in FIGS. 2a-c . This prevents the user from being able to have the collar 11 arranged around the neck when the collar is in its resting position. This resting or carrying position is beneficial if the user 3 is not doing the intended activity, but still wants to carry around the airbag system for practical reasons. If the intended activity is riding a bicycle, the user 3 may for example put the airbag system 100 in a resting position when he/she is entering a store to do some shopping before riding the bicycle again.

Three different resting positions are shown in FIGS. 2a-c , where the diameter of the collar is reduced by connecting different parts of the collar 11 by connecting means 9. The connecting means 9 may be zippers, buttons, Velcro fastening, magnets, hooks, hanks, buckles, safety pins, straps or the like. The collar 11 may for example be arranged in a spiral shape (as in FIG. 2a ), in a bottle-shape (as in FIG. 2b ) or in a heart shape (as in FIG. 2c ).

In the embodiment shown in FIG. 3, the collar 11, shown in an open state, is provided with an outer shell or cover 13 which encloses the airbag 20 when the airbag 20 is in an uninflated state. The outer shell 13 may be coloured or provided with a pattern. The user 3 may exchange the outer shell 13 in order to update the look of the collar 11. The outer shell 13 is attached to the collar 11 by means of e.g. zippers, Velcro, buttons, or any other suitable fastening means.

In order to adapt the collar 11 such that it suits different users it is preferred if the dimensions of the collar 11 are alterable. If the size of the collar 11 is fixed, a user 3 may not be able to use it if he/she is wearing e.g. a scarf or a high-necked piece of clothing, or wearing the collar 11 becomes uncomfortable. Therefore, the collar 11 is provided with size adjustment means such that the ergonomics of the collar 11 is improved.

In FIG. 4 a collar 11 in an original non-adjusted state is disclosed. From the outside of the collar 11 and inwards are the following portions arranged: outer shell 13, outer piece of material of airbag 121 b, inner piece of material of airbag 121 a, and again outer shell 13. The unadjusted collar 11 has a diameter D.

The size adjustment means may e.g. comprise a set of pads 15, an elongate pad 16, an inflatable tube 19, an elastic band 23, at least one elastic strap 26 a, 26 b or one or more additional shell 13′. The size adjustment means preferably comprises at least one strap 56 a, 56 b arranged through a fastening means 58 comprising a spool or arranged in two loops divided by a fastening means 58. In one embodiment, the size adjustment means comprises a set of pads 15. The pads 15 can be positioned at the shell 13, either on its interior side or its exterior side such that the inner diameter of the collar 11 is decreased. In FIG. 5 the collar 11 is disclosed in an adjusted state, with a number of pads 15 inserted at the exterior side of the outer shell 13 and facing the neck of an intended user. The diameter of the collar 11 is thus decreased and measures d, where d<D.

The size of the pads 15 may vary such that different sizes, i.e. diameters, of the collar 11 can be obtained. Also the number of pads 15 used can be chosen by the user 3 such that the collar 11 is optimally adjusted to him/her. As is readily understood the pads 15 could also be positioned on the inner side of the shell 13, i.e. between the shell 13 and inner piece of material of airbag 121 a.

Another option, shown in FIG. 6, is to use an elongate pad 16, which is arranged either between the outer shell 13 and the inner piece of material 121 a of the outer bag 22 or on the exterior side of the shell 13, facing the neck of the intended user. The diameter of the collar 11 is thus decreased and measures d, where d<D. Elongate pads 16 of different dimensions may be available such that the user 3 have different adjustment options and may adjust the diameter of the collar 11 accordingly. The elongate pad 16 may in one embodiment be inserted into the outer shell 13 from the joint portion provided with interlocking means 12. In another embodiment, shown in FIG. 7, the outer shell 13 comprises a closable opening 18 along the entire, or part of a longitudinal portion 17 of the collar 11, perpendicular to the joint portion, through which the elongate pad 16 may be inserted.

In another embodiment, shown in FIG. 8, an inflatable tube 19 is located within the outer shell 13, or on the exterior side of the shell 13 facing the neck of the intended user. By keeping the tube 19 uninflated the collar 11 maintains its largest possible diameter D. By inflation of the tube 19 a stepless adjustment of the diameter towards a smaller diameter d is obtained. The collar 11 comprises a valve 30 by which the tube 19 can be inflated. In one embodiment, the collar 11 comprises a built-in pump 31 for inflation of the tube 19. The pump 31 may be accommodated inside the shell 13 were it is protected when not in use. Alternatively, the pump 31 is attached to the outside of the shell 13 for easy access, e.g. with Velcro, a strap, a pocket or any other suitable attachment means (not shown). In another embodiment, an external pump (not shown) is used for the inflation of the tube 19.

In another embodiment, the size adjustment means comprises an elastic band, or strap, 23. The elastic band 23 may e.g. be located between the shell 13 and the outer piece of material 121 b of the airbag 20. In order to adjust the size of the collar 11 the elastic band 23 is stretched and fastened by means of suitable fastening means 24 either to the shell 13 or to the airbag 20 such that the band 23 is kept in its stretched state. Thus the size of the collar 11 is decreased. This is shown in FIGS. 9-10. The fastening means 24 may be a clamping device for stepless adjustment of the size, or a button or hooking device providing stepwise adjustment. The width and elasticity of the band 23 is adapted according to the width and rigidity of the collar 11. In another embodiment, several elastic bands 23 are provided in parallel and individually attached to the shell 13 or to the airbag 20 by means of the fastening means 24.

As another option, shown in FIG. 11, the size adjustment means is an additional detachable shell 13′. The largest size of the collar 11 is obtained by the shell 13 for which the state of the airbag 20 is unaffected when inserted into the shell 13, i.e. the size of the shell 13 is only slightly larger than the airbag 20, as shown in the previous embodiments. A smaller size of the collar 11 is obtained by fitting the airbag 20 into the shell 13′ having a smaller size compared to the size of the airbag 20. Thus, the airbag 20 is more or less compressed, corrugated or creased, and a smaller size of the collar 11 is achieved. The set of shells 13, 13′ may comprise additional, even smaller shells (not shown) for a stepwise adjustment of the size of the collar 11.

In yet another option, shown in FIG. 12, the size adjustment means comprises at least one elastic strap 26 a, 26 b arranged along the length of the collar 11. In order to adjust the size of the collar 11 the elastic strap 26 a, 26 b are stretched and fastened by means of suitable strap fastening means 28 either to the shell 13 or to the airbag 20 such that the strap 26 a, 26 b is kept in its stretched state. Thus the size of the collar 11 is decreased. By releasing the strap fastening means 28, the strap return to its unstretched state and the size of the collar is increased.

In FIG. 12, two elastic straps 26 a, 26 b are shown but it should be understood that any number of straps could be used to adjust the size of the collar 11. In the embodiment shown in FIG. 12 the elastic straps 26 a, 26 b are arranged on an inside wall of the shell 13. In yet one embodiment the elastic straps 26 a, 26 b are provided between the airbag 20 and the shell 13. The elastic straps 26 a, 26 b may also be arranged at the exterior side of the shell 13 facing the neck of an intended user.

The outer shell 13 comprises a number of openings 27 a, 27 b corresponding to the number of elastic straps. The openings 27 a, 27 b may be arranged either on the side facing the neck of an intended user or on the opposite side. Preferably, the openings 27 a, 27 b are arranged in close conjunction to each end of the joint portion provided with an interlocking means 12. The openings 27 a, 27 b are arranged to receive the elastic straps 26 a, 26 b so that the user can pull the straps 26 a, 26 b until a desired diameter of the collar 11 is achieved. Once the user pulls the straps 26 a, 26 b at each end, the size of the collar is decreased. At each end of the collar 11, at the joint portion, a strap fastening means 28 is arranged. The strap fastening means 28 prevents the elastic straps 26 a, 26 b from moving unintentionally. Preferably, the strap fastening means 28 is a plate shaped device having openings adapted for receiving the straps 26 a, 26 b. The ends of the elastic straps 26 a, 26 b may be tied or arranged with an end piece so as to ensure that the straps 26 a, 26 b are attached to the strap fastening means 28.

FIGS. 13a-b show yet another embodiment of a size adjustment means. FIG. 13a shows the side of the shell 13 that is facing the intended neck of the user and FIG. 13b is shown from the opposite side. The size adjustment means comprises at least one elastic strap 26 a, 26 b arranged along the length of the collar 11. The at least one elastic strap 26 a, 26 b may be provided either between the airbag 20 and the shell 13, arranged on an inside wall of the shell 13 or arranged at the exterior side of the shell 13 facing the neck of an intended user. In the embodiment shown in FIGS. 13a-b , the at least one strap 26 a, 26 b is arranged such that the end portion of the strap 26 a, 26 b extends through openings 27 a, 27 b arranged in the shell 13 such that the least one strap 26 a, 26 b at least partly extends on both longitudinal sides of the shell 13.

In the embodiment illustrated in FIGS. 13a-b the at least one strap is in the form of a loop, such as a rubber band. In order to adjust the size of the collar 11 the end portions of the straps 26 a, 26 b are fastened by means of suitable strap fastening means 28 such that the elastic straps 26 a, 26 b are stretched and the size of the collar is decreased. The fastening means 28 is preferably arranged such that it is in easy reach by the intended user without coming into contact with the enclosed airbag and electronics. The fastening means 28 may for example be arranged at the exterior side of the shell 13 on the opposite side of the side facing the neck of an intended user, as illustrated in FIG. 13b . By releasing the at least one strap 26 a, 26 b from the strap fastening means 28, the strap returns to its unstretched state and the size of the collar is increased. Preferably, the fastening means 28 comprises a plurality of means 29 for fastening the at least one loop strap 26 a, 26 b for allowing different tension and length of the strap(s). The fastening means 28 may for example comprise a plurality of protrusions 29 spaced apart from each other. The protrusions 29 may for example be a button or similar protruding element. The user fastens the loop of the at least one strap 26 a, 26 b around a protrusion(s) being arranged such that it provides a suitable size of the collar.

FIG. 14 shows yet another embodiment of a size adjustment means. In FIG. 14 the side of the shell 13 that is facing the intended neck of the user is shown. The size adjustment means comprises two straps 40, 42. Each strap 40, 42 is attached at one respective end of the collar 11. The opposite end of each strap 40, 42 is provided with attachment means, such as push buttons 44, 46. The straps 40, 42 may e.g. extend in a pocket 48 extending along the inner side of the collar 11. The pocket 48 may have a slit 49 arranged centrally through which the free end of the straps 40, 42 can be accessed. In the shown example each strap 40, 42 is provided with three sets of push buttons 44, 46. Depending on how these are attached to each other it is possible to adjust the length of the interconnected straps 40, 42 and thereby provide size adjustment of the collar 11.

FIG. 15 shows an embodiment of a size adjustment means. FIG. 15 shows the side of the shell 13 that is facing the intended neck of the user. The size adjustment means comprises at least one strap 56 a, 56 b arranged along the length of the collar 11. The at least one strap 56 a, 56 b may be provided either between the airbag 20 and the shell 13, arranged on an inside wall of the shell 13 or arranged at the exterior side of the shell 13 facing the neck of an intended user. In the embodiment shown in FIG. 15, the at least one strap 56 a, 56 b is arranged such that the end portion of the strap 56 a, 56 b extends through openings 57 a, 57 b arranged in the shell 13 such that the least one strap 56 a, 56 b at least partly extends on both longitudinal sides of the shell 13.

In the embodiment illustrated in FIG. 15 the at least one strap 56 a, 56 b is in the form of a loop, such as a rubber band. In order to adjust the size of the collar 11 the end portions of the straps 56 a, 56 b are fastened by means of suitable strap fastening means 58 such that each strap 56 a, 56 b is divided into two loops with the strap fastening means 58 between them, wherein a first loop 59 a extends around the collar 11 and a second, preferably smaller loop 59 b extends freely from the strap fastening means 58. The size of the first loop 59 a is inversely proportional to the size of the second loop 59 b. If the size of the second loop 59 b is extended, for example by adjusting the strap fastening means 58 or by pulling at the second loop 59 b, the size of the first loop 59 a is decreased since the at least one strap 56 a, 56 b is relatively fixed in size and therefore the size of the collar 11 is decreased. The at least one strap 56 a, 56 b may be elastic and may be very slightly elastic or rigid. By adjusting the sizes of the first and second loops 59 a, 59 b, different tension and length of the collar 11 is allowed. The fastening means 58 is preferably arranged such that it is in easy reach by the intended user without coming into contact with the enclosed airbag and electronics. The fastening means 58 may for example be arranged at the exterior side of the shell 13 on the opposite side of the side facing the neck of an intended user, as illustrated in FIG. 15. The fastening means may for example comprise a clamp, a spool or a combination of the two. The at least one strap 56 a, 56 b may be arranged to have a preferred state when the first loop 59 a is as big or almost as big as is possible. This may preferably be done by using the elastic or non-elastic properties of the strap. By releasing the at least one strap 56 a, 56 b from the strap fastening means 58, the strap returns to its preferred state which increases the size of the first loop 59 a, in turn increasing the size of the collar 11. The user fastens the loops 59 a, 59 b of the at least one strap 56 a, 56 b in the fastening means 58 such that it provides a suitable size of the collar 11.

In a further, preferred embodiment the size adjusting means includes only one strap being maneuverable by means of a fastening means 58; the fastening means 58 may in such embodiment have a spool member inside a housing. The strap is secured to the spool member such that when the spool member is rotated in a tightening direction (e.g. by means of a knob or similar), the strap will be drawn into the housing. The spool member may have spool teeth around its periphery, such that the spool member is locked in position after desired tightening. Release of the spool member may e.g. be achieved by pulling the knob axially away from the housing. In case the spool member is spring biased, automatic untightening of the strap will be immediately effected. A feature in common for all the above described embodiments is that it is the outer shell 13 that decides the maximum size, i.e. the diameter D of the collar 11. The size can be adjusted to become smaller in order to suit the individual user 3. An advantage relevant for all embodiments is that the user ergonomics is improved. 

1. An airbag system comprising an airbag and a detachable shell enclosing the airbag when the airbag is in a non-inflated state, and at least one size adjustment mechanism.
 2. The airbag system according to claim 1, wherein the airbag system is arranged as a collar, wherein the size adjustment mechanism is arranged to adjust a diameter of the collar from a larger diameter (D) to a smaller diameter (d).
 3. The airbag system according to claim 1, wherein the at least one size adjustment mechanism comprises a set of pads, arrangeable between the airbag and the shell or at an exterior side of the shell facing a neck of an intended user.
 4. The airbag system according to claim 1, wherein the at least one size adjustment mechanism comprises an elongate pad, arrangeable between the airbag and the shell or at an exterior side of the shell facing a neck of an intended user.
 5. The airbag system according to claim 1, wherein the at least one size adjustment mechanism comprises an elastic band, arrangeable between the airbag and the shell, at an exterior side of the shell facing a neck of an intended user or at an inside wall of the shell.
 6. The airbag system according to claim 1, wherein the size adjustment mechanism comprises a set of additional detachable shells having smaller sizes compared to the detachable shell.
 7. The airbag system according to claim 1, wherein the size adjustment mechanism is an inflatable tube, and wherein the airbag system further comprises a valve for inflation of the inflatable tube.
 8. The airbag system according to claim 7, further comprising a pump for inflation of the inflatable tube.
 9. The airbag system according to claim 2, wherein the at least one size adjustment mechanism comprises at least one elastic strap, arrangeable between the airbag and the shell, at an exterior side of the shell facing a neck of an intended user or at an inside wall of the shell.
 10. The airbag system according to claim 9, wherein the size adjustment mechanism further comprises a strap fastener arranged at each end of the collar to fasten the at least one elastic strap when a desired diameter of the collar is achieved.
 11. The airbag system according to claim 10, wherein the strap fastener is a plate shaped device having openings adapted for receiving the elastic straps.
 12. The airbag system according to claim 9, wherein the size adjustment mechanism further comprises a strap fastener arranged at the exterior side of the shell which is not facing the neck of the intended user.
 13. The airbag system according to claim 12, wherein the strap fastener comprises a plurality of protrusions to fasten the at least one elastic strap.
 14. The airbag system according to claim 2, wherein the at least one size adjustment mechanism comprises at least one strap in the form of a loop, arrangeable between the airbag and the shell, at an exterior side of the shell facing a neck of an intended user or at an inside wall of the shell.
 15. The airbag system according to claim 14, wherein the size adjustment mechanism further comprises a strap fastener arranged at an end of the collar to fasten the at least one strap such that each strap is arranged through the strap fastener.
 16. The airbag system according to claim 15, wherein the strap fastener comprises a spool member inside a housing.
 17. The airbag system according to claim 16, wherein the at least one strap is secured to the spool member such that when the spool member is rotated in a tightening direction, the at least one strap will be drawn into the housing.
 18. The airbag system according to claim 17, wherein the spool member has teeth around its periphery such that the spool member is locked in position after desired tightening.
 19. The airbag system according to claim 17, wherein the spool member is spring biased.
 20. The airbag system according to claim 15, wherein the strap fastener is arranged such that each strap is divided into two loops with the strap fastener between them.
 21. The airbag system according to claim 20, wherein the strap fastener divides the at least one strap into a first loop, which extends around the collar, and a second loop, which extends freely from the strap fastener.
 22. The airbag system according to claim 21, wherein the first loop is larger than the second loop.
 23. The airbag system according to claim 21, wherein a size of the first loop is inversely proportional to a size of the second loop.
 24. The airbag system according to claim 23, wherein the strap fastener are arranged to fasten the at least one strap when a desired diameter of the collar is achieved.
 25. The airbag system according to claim 15, wherein the strap fastener comprises a clamp and a spool.
 26. An inflatable helmet comprising an airbag system according claim
 1. 27. An item of apparel comprising the airbag system according to claim
 1. 28. The item of apparel according to claim 27, the item being a collar. 